Randy Olson Randy Olson - 1 month ago 10
Python Question

Is there an easy way to prune disconnected networks in a NetworkX graph?

I'm using Python's NetworkX package to calculate a bunch of network statistics for networks of varying size. I'm sweeping an independent parameter that systematically prunes edges, so sometimes a small network will become disconnected from the main network. Is there an easy way to detect and remove those smaller disconnected networks in NetworkX?

Answer

Sorin is correct. The function is called connected_component_subgraphs in NetworkX.

Documentation: http://networkx.github.io/documentation/latest/reference/generated/networkx.algorithms.components.connected.connected_component_subgraphs.html#networkx.algorithms.components.connected.connected_component_subgraphs

Here's some code that finds the largest network in a NetworkX graph:

cur_graph = # whatever graph you're working with

if not nx.is_connected(cur_graph):
    # get a list of unconnected networks
    sub_graphs = nx.connected_component_subgraphs(cur_graph)

    main_graph = sub_graphs[0]

    # find the largest network in that list
    for sg in sub_graphs:
        if len(sg.nodes()) > len(main_graph.nodes()):
            main_graph = sg

    cur_graph = main_graph
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